The present disclosure relates to heat exchangers, and in particular to ram mounting flanges for plate fin heat exchangers.
Heat exchangers are often used to transfer heat between two fluids. For example, in aircraft environmental control systems, heat exchangers may be used to transfer heat between a relatively hot air source (e.g., bleed air from a gas turbine engine) and a relatively cool air source (e.g., ram air). Some heat exchangers, often referred to as plate fin heat exchangers, include a plate fin core having multiple heat transfer sheets arranged in layers to define air passages there between. Closure bars seal alternating inlets of hot air and cool air inlet sides of the core. Accordingly, hot air and cool air are directed through alternating passages to form alternating layers of hot and cool air within the core. Heat is transferred between the hot and cool air via the heat transfer sheets that separate the layers. In addition, to facilitate heat transfer between the layers, each of the passages can include heat transfer fins, often formed of corrugated material (e.g., aluminum), that are oriented in a direction of the flow within the passage. The heat transfer fins increase turbulence and a surface area that is exposed to the airflow, thereby enhancing heat transfer between the layers.
As hot air passes over components of the plate fin heat exchanger (e.g., closure bars, heat transfer fins, and other components), differing thermal expansion properties of the various components can cause the components to expand at different rates. Overall expansion of the core is typically restricted by, for example, housings of the core or other peripheral components of the plate fin heat exchanger. Restricted thermal expansion of the core can cause thermally-induced stress to components of the core, thereby reducing longevity and reliability of the plate fin heat exchanger.